Kakashi's sharingan

[Rek]

actually, isn't the movie supposed to come out sometime this summer?

[-ANBU-Sasuke-]

This subject has been cut up to millions of pieces, no matter how you look at it, it's the same answer.

.........WE DON'T KNOW.

We only know that Kakashi's sharingan isn't his, from what Itachi said in the battle. Where Kakashi had received his Eye, is a mystery.

My opinon, remember when Kakashi faught zabuza, and when Haku came and took his body? Kakashi stated that people can use the body to find our secrets, such and Jutsu's and even his sharingan. SO in my theory, kakashi decided to go body hunting and steal a sharingan or some sort.
The scar on his eye, we can presume that it is a surgical scar due to the given facts:

1.Not Uchiha
2.Scar that happends to be on the eye of the sharingan

Even if we knew where his eye came from, what differance does it make?